I've had them on my Inbred for the last couple of years and think they are perfect for what I do, which is mainly multi-day off road tours. The centre tread keeps them nice and quick on road and firm tracks and they're good enough for all the other off road situations I've used them in, though you can't hammer round loose corners the same way as you might with more aggressive tyres. Mine have seen a good mix of conditions:

Not bad on sheet ice!

They're tough enough for me as well as giving good cushioning in 2.25" size.

That's pictures from a few different tours The top two are from a Glen Tilt - Minigaig tour I did one winter and the rest from some coast to coast Scotland rides. The last is from an icy loop round Alladale I did a couple of weeks back. I never get many pictures with the bike in as I'm always the photographer! Nice pic Stu, I've always wanted to do something like that in the Himalayas if I could persuade the wife!

tbh i found them to be the worst tyres i've used. for touring i've just used fatter marathons (although not on singletrack stuff), and for off road touring i used NNs (which i also dislike).
i'd probably whack on a set of maxxis crossmarks, as i find them fast rolling, but also capable off road too. something which, ime, the smart sams just weren't.

though you can't hammer round loose corners the same way as you might with more aggressive tyres.

The loose cornering is pretty important to me as a lot of the trails over here are on very loose gravel, so something with very good cornering grip is important, but nice and fast rolling into the bargain if there is such a beast.

Maybe the Maxis Crossmarks would be a better bet.... Nice tyres are just so expensive now it's very easy to spend an absolute fortune on wrong choices.
I can stick a tyre on the car over here for less than the bike tyres in the LBS!

I'm normally out 5 days a week on a mixture of trails from completely gravel road to really rocky down hill routes, so it's always difficult to find the right all round tyre. I've used a Kenda Nevegal / Blue Groove mix up to now and been happy with them, but I noticed that the side knobles on this set have started to come away from the tyre casing in places, so with that in mind and the fact that I can't get them locally anymore I decided to have a change. The LBS stocks Schwalbe and Maxxis, hence my interest in these.
They have some Nobby Nics with the snakeskin protection which should be good for the cactus thorns, so I might try those.

I personally find the NN rolls really badly compared to others in the Schwalbe range. I use the 2.25 snakeskin Sam on the rear for most trail centre duties with an albert on the front. for racing I'm now on the Rocket Ron or Ralph. I find the Sam rolls well with it having the almost continuous centre band but not much cop for braking on the front, hence the Albert on the front.